Percutaneous catheter-based treatments of cardiovascular disease require that navigation of the catheter within the body be done with a mode of visualizing the catheter as it is moved within the body. The most popular mode of visualization is X-ray fluoroscopy, where an operator is able to monitor a radiopaque device as it travels within a body lumen, such as the cardiovascular system.
Recently, interventional procedures that require catheter navigation within the chambers of the heart have been developed; these include electrophysiological mapping and ablation and transmyocardial revascularization. These procedures also often require that the tip of the catheter be placed in contact with a wall of the beating heart in order to deliver the desired treatment safely. Potential complications of this procedure may be perforation of the wall when excessive force is applied or ineffective treatment due to poor tip contact. Under fluoroscopic guidance it is often difficult to assess when the catheter tip has reached the wall because live fluoroscopy does not visualize that wall itself, since it is not radiopaque. For the same reason, even after the catheter tip has reached the wall, it is difficult to determine whether the tip consistently remains in contact with the wall or if excessive force is applied to the wall. Finally, it is also difficult to determine whether the catheter tip is substantially perpendicular to the wall because fluoroscopy yields a two-dimensional image of the device in three-dimensional space.
Thus, for procedures where a medical instrument must be placed in firm but not excessive contact with an anatomical surface, there is an apparent need for a device which is able to provide information to the user of the instrument that is indicative of the existence and magnitude of the contact force. Furthermore, for procedures where the medical instrument must also be placed either perpendicular or at some selected angle to the anatomical surface, there is an apparent need for a device which is able to provide information to the user of the instrument that is indicative of the incident angle of the contact force with respect to the anatomical surface.